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目的研究不同机架旋转时间对64层螺旋CT图像质量的影响。方法使用SOMATOM Sensation 64层螺旋CT。把del-ta模体沿Z轴固定于CT机架的中心,使用腹部螺旋扫描模式,进行扫描和重建,然后制作各位置图像序列的层敏感度曲线(SSP),并对各图像序列的SSP进行傅里叶变换得到调制传递函数(MTF)。后用腹部螺旋扫描模式对CT质控模体Catphan500进行扫描和重建,分别记录图像的最大线对数及其能分辨的各级对比度的最小目标的尺寸。结果0.5s组和1s组的MTF曲线几乎重合,5%MTF值分别为11.3LP/cm和11.9LP/cm;其空间分辨率和低对比度分辨率也完全相同。结论机架旋转时间0.5s组和1s组图像质量无差别。为缩短扫描时间,消除呼吸伪影,我们建议在腹部螺旋扫描时,机架旋转时间0.5作为常规应用。
Objective To study the effects of different rack rotation times on the quality of 64-slice spiral CT images. Methods SOMATOM Sensation 64-slice spiral CT was used. The del-ta phantom is fixed to the center of the CT gantry along the Z-axis and scanned and reconstructed using the abdomen helical scan mode. The layer sensitivity curve (SSP) of each position image sequence is then generated and the SSP The Fourier transform is performed to obtain a modulation transfer function (MTF). After scanning and reconstructing the CT control phantom, Catphan 500, the abdominal spiral scan mode was used to record the maximum line logarithm of the image and the minimum target size of each contrast that can be resolved. Results The MTF curves of 0.5s group and 1s group almost coincided with 5% MTF values of 11.3LP / cm and 11.9LP / cm, respectively. The spatial resolution and the low contrast resolution were also the same. Conclusion There is no difference in image quality between 0.5s and 1s for the rack rotation time. In order to shorten the scan time and eliminate respiratory artifacts, we recommend that the rack rotation time 0.5 be used as a routine application during abdominal helical scanning.